All manner of shutoff valves are used in fluid systems to interrupt flow of fluid to a target. Shutting off the flow may be for purposes of avoiding overfilling a storage vessel or the like, halting draining, or for a variety of other purposes. In internal combustion engine systems, it can be desirable in certain applications to provide a mechanism for rapidly shutting off a supply of air to the engine. Various strategies for engine shutdown have been proposed over the years. It has been observed, however, that starving the engine of air is commonly the most effective and reliable way to stop operation quickly. Engines used in certain environments where combustible gases are present can present a particular need for rapid engine shutdown.
At a wellhead, for example, combustible gases such as natural gas can sometimes leak, or otherwise escape, from a bore hole or containment vessel. Engines operating in such environments can end up being supplied with extra fuel in the form of natural gas entering the air intake system, having undesirable consequences such as engine overspeeding. In other instances, engines can overspeed on other combustible fuel such as wood chips, alcohol, gasoline vapors, hydrogen, in enriched oxygen atmospheres, or even on their own oil supply or diesel fuel supply such as in the case of a stuck fuel rack or the like. Swing gate air shutoff valves, for instance, provide a gate that pivots within a housing to obstruct an air supply conduit in an engine air intake system. Such shutoff valves can experience relatively harsh conditions including vibration excitation from the engine, and temperature extremes.
United States Patent Application Publication No. 2015/0315983 relates to a method and apparatus for shutting down an engine by selectively preventing air from passing into the air intake. According to the '983 publication, a valve in the nature of a butterfly valve is electromagnetically actuated to move to a closed position to prevent air from passing into the engine air intake once one or more predetermined engine conditions have been detected. While the disclosed strategy may have certain applications, there are likely disadvantages relating to reliability, false tripping, or performance degradation over time.